Heterointegrated Ga ₂ O ₃ -on-SiC RF MOSFETs With <i>f</i> _T / <i>f</i> _max of 47/51 GHz by Ion-Cutting Process

Abstract

Heterointegrated Ga2O3-on-SiC radio-frequency (RF) MOSFETs with record-high frequency performances were reported. A two-dimensional electron gas like channel with a high electron concentration and decent mobility was formed through the shallow implantation of Si into the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 (−201) nanomembrane integrated on the highly thermal conductive 4H-SiC substrate through an ion-cutting process. The resultant MOSFET yields a high current density of 661 mA/mm and a transconductance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}_{\text {m}}{)}$ </tex-math></inline-formula> of 57 mS/mm. A record-high current cut-off frequency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{\text {T}}{)}$ </tex-math></inline-formula> of 47 GHz and maximum oscillation frequency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{\text {max}}{)}$ </tex-math></inline-formula> of 51 GHz were achieved with the gate length ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {G}}{)}$ </tex-math></inline-formula> scaled down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.1~\mu \text{m}$ </tex-math></inline-formula> . Furthermore, the device with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {G}}= 0.1\,\,\mu \text{m}$ </tex-math></inline-formula> showcases an output power density of 296 mW/mm and a high power gain of 11 dB at 2 GHz in continue wave (CW) mode. It is attributed to the enhanced gate control, elevated current output, and improved thermal conductivity of the heterointegrated Ga2O3 on SiC by ion-cutting process.